When satellites are launched to orbit (regardless of orbit type) there is often some launch vehicle mass and volume capacity that is not used. One purpose of the system disclosed herein is to use this surplus volume and mass capacity to deliver additional and separate payloads to orbit, from where the payload can proceed with its intended mission. This concept of delivering hosted payloads to particular orbits is described in “DARPA Phoenix Payload Orbital Delivery (POD) System: “FedEx to GEO”, Dr. Brook Sullivan et al, AAAIAA Space 2013 Conference and Exposition, Sep. 10-12, 2013, San Diego, Calif. As described in this paper, a payload includes but is not limited to such space systems as another small (micro or nano) spacecraft, replacement materials (e.g. fuel) to replenish another satellite, replacement components for on-orbit servicing repair of another spacecraft, components for in-space assembly of a new space system or spacecraft.
Current orbital payload ejection systems require that the payload centre of mass be closely aligned with the centre of force of the ejection mechanism or else significant tumble rates (undesired angular rates and translational velocities transverse to the ejection axis at the time of release) are created at ejection, which is almost always considered a very negative condition. Accommodating an offset between the mechanism centre of force and the payload centre of mass that remains unknown, but within a prescribed volume, at launch allows for increased flexibility in accommodating payloads. This flexibility is particularly beneficial if there are multiple payload parts that may have specific packaging requirements or irregular shapes. Similarly, endeavouring to make the prescribed volume for the centre of gravity as large as possible maximises the payload accommodation flexibility.
The current state of the art either uses an array of separation springs (e.g. the commercially available Lightband™) that can induce a significant tumble rate if the center of mass is spaced from the ejection mechanism geometric center, or a guide rail system (i.e. Pico-Satellite Orbital Deployer PPOD) for very small payloads (nano-sats) that does not scale well to larger payloads—in excess of tens of kilograms up to a few hundred kilograms—and, further, would be at risk of jamming or binding upon release.
Existing ejection methods are unable to eject a payload with an offset center of mass without causing the payload to tumble. This is a result of the ejection technique; many existing methods exert a force or forces that are on, or average to, the geometric center of the ejection device. If the center of mass of the payload is offset from this geometric center of the ejection device, the payload will tumble. A common technique in the industry is to use springs to eject a payload. If the payload center of mass is offset from the geometric center, the force upon the springs is not evenly distributed. This results in the payload tumbling when the springs are released.